BOBBY JINDAL GOVERNOR PEGGY M. HATCH SECRETARY

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# of JLouisiana DEPARTMENT OF ENVIRONMENTAL QUALITY 

### ENVIRONMENTAL SERVICES Mr. Thomas H. Diggs Associate Director, AirPrograms (6PD) U.S. Environmental Protection Agency, Region 6 1445 Ross Avenue, Suite 1200 Dallas, TX 75202-2733 DearMr. Diggs: This letter serves to clarify the Louisiana Department of Environmental Quality's (LDEQ's) positionregarding the use ofPMlO as a surrogate for PMZ.5. EPA's final rule entitled "Implementation of the New Source Review (NSR) Program for Particulate Matter Less Than 2.5 Micrometers (PMZ .5

)," was promulgated on May 16,2008. 1 In this rule, EPA acknowledges that: States with SIP-approved PSD [Prevention ofSignificant Deterioration] programs that require amendments to incorporate these final NSR rule changes for PMZ.5 will need time to accomplish these SIP amendments. For example, a State may need to amend its existing regulations to add the specific significant emissions rate for PM2.5 or a designatedprecursor.Z Accordingly, the rule specifies that states with SIP-approved PSD programs, like Louisiana, must submit revised PSD and Nonattainment New Source Review (NNSR) programs for PMZ .5 by May 16, 2011.3 EPA further elaborates on applicable requirements during the "transition" period, then concludes withwhy the agencybelieves this approach is reasonable. During this SIP development period, the PMz.5 NAAQS must still be protected under the PSD program in such States. We are finalizing our proposed option 1 that ifa SIP-approved State is unable to implement a PSD program for the PMz.5 NAAQS based on these final rules, the State may continue to implement a PMlO program as a surrogate to meet the PSD program requirements for PMZ .5pursuant to the 1997 guidance mentionedpreviously [i.e., the PMlO Surrogate Policy].4 We believe that our final rule is reasonable for the following reasons. First, PMlO will act as an adequate surrogate for PMZ .5 in most respects, because all new major sources and major modifications that would trigger PSD requirements for PMz .5 would also trigger PMlO requirements because PMZ .5 is a subset ofPMlO. Second, both of the precursors designated in the final rule

- SOz and NOx (presumptively)

- are already regulated under State NSR programs for other criteria pollutants. Thus, those precursors will be subject to NSR through those otherprograms.5

1 73 FR28321 2 73 FR28340 3 73 FR28341 4 Ibid. 5 Ibid. Post Office Box4313 • Baton Rouge, Louisiana 70821-4313 • Phone 225-219-3181 • Fax 225-219-3309 www.deq.louisiana.govMr. Thomas H. Diggs Page 2

On February 11, 2010, EPA proposed to end early the PMlO Surrogate Policy applicable to SIPapproved states; however, this proposal has notbeen finalized to date. 6 Louisianahas not yet adopted the provisions ofEPA's PM2.5 NSRImplementation Rule, butwill propose arule to do so in early 2011. In the interim, in light of"In the Matter of: Louisville Gas and Electric Company" (Petition IV2008-3) andEPA's directive thatpermitting authorities must "demonstratethatPMlO is areasonable surrogate for PM2 .5

," LDEQ is generally requiring all applicants proposing significant increases in PM2 .5emissions which would be subjectto PSD review underthe federal programto conduct both BACT and air quality impact analyses. However, should LDEQ choose to rely on EPA's PMlO Surrogate Policy, LDEQ will not proceed on the general presumption that PM10 is always a reasonable surrogate for PM2.5 and will include in the permit record an adequate rationale or demonstration to support the use ofPMlO as a surrogate based on thefacts and circumstances of the specific perinit action. Should you have any questions concerning this matter, please feel free to contact Bryan D. Johnston ofthe AirPermits Division at (225) 219-3450. Sincerely,



# UUc-- Cheryl SonnierNolan Assistant Secretary CSN:BDJ

6 75 FR 6827

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